Quality control plan
|Quality control plan|
|Methods and techniques|
Quality control plan is a document that describes product, service or process characteristics that should be monitored in order to achieve expected result. The plan helps to increase and keep the discipline in the process, which leads to better stability and more predictable results.
Types of quality control plans
The main types of plans are:
- Process quality control plan - describes characteristics of the process
- Product/service quality control plan - describes characteristics of the product/service
- Project quality control plan - describes quality control in project management
- PDCA quality control plan - used in improvement and corrective actions to evaluate their results
Structure of the plan
There is no one standard for quality control plan, however every plan will contain several common elements. The key elements of the plan are:
- Description of object being the subject of the plan
- Responsibility and entitlements of staff
- Preliminary checks - things to check before the beginning of the process, project, etc.
- Initial checks - things to check during initialization of the process, production
- Sampling methods - during the process usually only samples should be monitored
- Final checks - things to check prior to or after finishing
- Reaction to defects - description how to react when defects are found
- Reporting (what, to whom and how often)
Sampling in quality control
Sampling can be based on agreements or internal/external standards that define acceptable quality level (AQL). The main types of sampling are:
- single-stage sampling plan,
- double-stage sampling plan,
- accept on zero,
- continuous sampling.
Sampling was described in detail in separate article.
Off-line and on-line quality control
Off-line quality control is related to prevention of failures. On-line quality control is related to real-time production. Both were described in article Quality control.
Benefits of planning quality control
The quality control takes time and gives no profits (at first sight). Therefore it is too often skipped or reduced below reasonable level. Quality control planning helps to prevent this. Moreover it:
- Provides a summary of our knowledge about process/product/project
- Keeps requirements visible
- Describes data used to performance evaluation
- Describes what to do in case of quality problems
- Shows the roles of the staff
Quality plan vs. quality control plan
In many publications the quality control plan is misunderstood as quality plan. Quality plan describes actions planned in order to improve quality, while quality control plan is used to only monitor whether the quality is consistent with specification.
The content of the quality plan, according to ISO 9001:2015 should consist of:
- What it is to be done,
- What resources will be required (financial, material, knowledge, etc.),
- Who will be responsible for the effects,
- When should it be finished,
- How the results will be evaluated.
- Evans, J. R., & Lindsay, W. M. (1999). The management and control of quality.
- Kackar, R. N. (1989). Off-line quality control, parameter design, and the Taguchi method. In Quality Control, Robust Design, and the Taguchi Method (pp. 51-76). Springer US.
- Knappenberger, H. A., & Grandage, A. H. E. (1969). Minimum cost quality control tests. AIIE Transactions, 1(1), 24-32.
- Control plan on ASQ
Author: Slawomir Wawak